Photos from a different event appearing in Events from My Mac on iPhone.

I synced my iPhone with iTunes in order to have the photos from a new Mac iPhoto event appear on the iPhone. The event synced, and most of the photos are on the iPhone, but there are random photos within it that are the wrong ones. They are from an entirely different event from over a year ago. I went back to iPhoto to check, and it is all correct there, none of the rogue photos are actually in this new event. Any suggestions as to how to change this please?